Occasional Freeze

Sometimes upon booting up and often after resuming from Sleep Win 7 will freeze after starting any program.
Diagnostics shoes nothing, no virus or malware...

Couple of things you can do. Run a few more on-demand malware scans. No anti-malware product is 100% effective 100% of the time. If there was such a thing we'd all be using it. Some recommended products are:

Malwarebytes

ESET Online Scanner

Windows Defender Offline

Also suggest checking for any damaged or corrupt system files by running a system file checker scan from an elevated command prompt (option two.) If problems are found, run the scan 3 times and reboot the computer after each scan.

SFC /SCANNOW Command - System File Checker

You could also go through this troubleshooting guide prepared by one of the Forum experts.

Troubleshooting Windows 7 Failure to Boot

Try removing malwarebytes after you do your checks,i had the same problem with random lock ups removing malwarebytes solved it.worth a try

Except for using Malwarebytes, which I have used for years, I went through all these checks.